1.Field of the Invention
This invention relates to a novel method for the production of a perfluoro-cyclic imine. More particularly, this invention relates to a method for producing a perfluoro-cyclic imine useful as an intermediate for the synthesis of such fluorine-containing products as surfactants, agricultural pesticides, and medicines or a macromolecular monomer by the use of a readily available raw material, economically with a high yield.
2. Description of the Prior Art
In recent years, the fluorine-containing olefin compounds have been interested as intermediates or raw materials for the synthesis of various fluorine-containing products. They have been found extensive utility as intermediates for the synthesis of surfactants, agricultural pesticides, and medicines and as monomers for the production of fluorine-containing polymers.
Since perfluoro-cyclic imines, which are a type of such fluorine-containing olefin compounds, have a double bond between a carbon atom and a nitrogen atom in the cycle, they can easily react with a nucleophilic reagent. By using these compounds as intermediate raw materials, therefore, various compounds having a functional group linked to a nitrogen atom can be produced. Perfluoro-cyclic imine derivatives have been found useful for intermediates for surfactants, agricultural pesticides, and medicines.
Perfluoro-cyclic imines have already known in previous literatures and are produced by thermal decomposition of a corresponding secondary perfluoro-cyclic amine with/without a catalyst. Nonafluoro-2,3,4,5-tetrahydro-pyridine is produced from undecafluoropiperidine ["Journal of Organic Chemistry," p. 2811 (1963) and Journal of Chemical Society, Perkin I, p. 1098 (1972)], 2,2,3,3,5,6,6-heptafluoro-3,6-dihydro-2H-&lt;1,4&gt;oxazine from nonafluoromorpholine ["Journal of Chemical Society," p. 6077 (1965)], and heptafluoro-3,4-dihydro-2H-pyrrole from nonafluoropyrrolidine ["Journal of Organic Chemistry," p. 2811 (1963)]. The undecafluoropiperidine and the nonafluoromorpholine which are synthesized by the method of electrolytic fluorination from the corresponding cyclic amines only in low yields. The nonafluoropyrrolidine could not be synthesized by the method of electrolytic fluorination and is synthesized by the reaction of tetrafluorosuccinonitrile with silver (II) fluoride in low yield too.
It has been also known that nonafluoro-2,3,4,5-tetrahydro-pyridine and 2,2,3,3,5,6,6-heptafluoro-3,6-dihydro-2H-&lt;1,4&gt;-oxazine are synthesized in small amounts by the thermal decomposition from potassium perfluoropiperidinopropionate and potassium perfluoromorpholinopropionate, respectively ["Chemistry Letters," p.907 (1989)]. These reactions yield perfluoro(N-vinyl piperidine) and perfluoro(N-vinyl morpholine) as main products and the desired perfluoro-cyclic imines as by-products in such small amounts as 13 to 21%. Thermal decomposition of these propionate, therefore, does not prove a practical approach to the synthesis of perfluoro-cyclic imines.
A strong need is felt for the development of a method for producing a perfluoro-cyclic imine useful as an intermediate for synthesis and as a monomer for the production of fluorine-containing polymers from an easily procurable raw material, economically with a high yield.
It is, therefore, an object of this invention to provide a method for the production of a perfluoro-cyclic imine.